For example, a nuclear power plant including a pressurized water reactor (PWR) uses light water as a reactor coolant and a neutron moderator, which is light water serving as a high-temperature and high-pressure water that does not boil over the reactor internal of the reactor, sends the high-temperature and high-pressure water to a steam generator to generate steam by heat exchange, and sends the steam to a turbine generator to generate power. The steam generator transmits the heat of a primary cooling water with a high temperature and a high pressure from the reactor to a secondary cooling water to generate steam with the secondary cooling water.
In such a nuclear power plant, when a loss-of-coolant accident occurs due to a break of a pipe in the reactor, it becomes difficult to sufficiently cool the reactor with the coolant. For this reason, the reactor is cooled urgently by pumping up the cooling water in a refueling water storage pit with a pump, supplying the cooling water into the reactor, spraying the cooling water toward the reactor from multiple spray nozzles that are arranged at an upper part of the containment. In this case, foreign matter caused due to the break of the pipe falls into the refueling water storage pit and, for this reason, a recirculation sump screen is placed on the top of the refueling water storage pit. Accordingly, the foreign matter is blocked by the recirculation sump screen to inhibit the foreign matter from entering the refueling water storage pit, which prevents the pumps and pipes from being damaged due to the foreign matter.
Note that there is the device according to the following Patent Document 1 as a reactor emergency cooling device.